Worldwide, peptic ulcer and gastritis considered to be one of the biggest health challenge, Helicobacter pylori is responsible for more than eighty percent of chronic active gastritis where continual infection remains for decennary. However, the success of commercially available drugs for the management of H. pylori has overwhelmed by antibiotic-resistant strains, especially, metronidazole and clarithromycin, therefore, an urgent need arise to search for new options for treatment with enhanced anti-H. pylori activities, while being less toxic to human cells. Naturally occurring plant products, including spices, are one of these strategies that showed activity against H.pylori. Present study aim to test the antibacterial activity of capsaicin and other pure plant-derived compounds against a standard (NCTC 11916) H. pylori strain In vitro and to test for possible synergistic effect when combined with conventional therapy. Capsaicin shows good antibacterial activity on regular antimicrobial sensitivity testing methods (Anti-MSTM) and titration checkerboard assay MIC (0.0625 mg/ml), whereas piperine MIC was (0.125 mg/ ml). While for curcumin no inhibition was found. The strain was found to be resistant to metronidazole with (MIC=250 μg/ml). When combining capsaicin with metronidazole, (FIC) Fractional inhibitory concentration values shown a synergistic effect, While the additive effect was found for capsaicin combination with piperine. Our obtained data indicate that capsaicin possesses promising anti H.pylori bioactivity and synergistic activity when combined with metronidazole but more work is necessary to examine the mechanisms by which these happened. Furthermore, it is necessary to ensure its activity against H.pylori In vivo and clinical settings.

Significance and Impact of the Study: Medicinal plants are traditionally used in Jordan for the treatment of different infections; numerous are reported to possess antibacterial activity against Staphylococcus aureus strains. Introducing safe drugs of natural origin to overcome the resistance problem and the side effect of common treatments have always been of great interest to scientists working in this field. In which the overall effect may act synergistically to inhibit bacterial growth.

The present study was conducted to assess the in vitro activities of folk medicinal plants in combination with levofloxacin against TG1 and mutant KAM3-1(∆acrB-∆tolC) Escherichia coli strains. Plants were chosen based on their traditional use in combination with antibiotics among laymen. Standard protocols were followed to examine the antimicrobial activity of plant extracts and levofloxacin against E. coli in term of their minimum inhibitory concentrations (MICs) and to evaluate the plant extracts-levofloxacin interaction using checkerboard method. Among the twelve plants investigated, Thymus vulgaris, Zingiber officinale, Teucrium polium, Matricaria chamomilla and Curcuma longa had the best antimicrobial activities against E. coli strains with MIC values at 250 μg/ml. It is noteworthy to mention that other folk plants extracts reveled no effects against E coli strains. Furthermore, additive interactions were observed between levofloxacin and T. polium or T. vulgaris against E. coli wild-type TG1 strain. There was no antagonism being observed in this study. The detection of additive interaction between the extracts and levofloxacin demonstrates the prospective of these folk medicinal plants as a source of compounds to modulate antibiotic resistance.